Process for the conversion of hydrocarbons employing a sulphided fluorine-containing nickel-tungsten catalyst

ABSTRACT

A process is disclosed for preparation of sulphided fluorine-containing nickel-tungsten catalyst having high activity in hydroconversion processes of hydrocarbons. A process for the conversion of hydrocarbons is also disclosed.

This is a division, of application Ser. No. 147,693, filed May 7, 1980,now U.S. Pat. No. 4,279,778.

BACKGROUND OF THE INVENTION

The invention relates to a process for the preparation of a sulphidedfluorine-containing nickel-tungsten catalyst.

Such catalysts and a process for their preparation are known from theNetherlands patent application 7514824. As starting material for thepreparation of such catalysts certain aluminum hydroxide hydrogels areused.

At least part of the fluorine is incorporated into an aluminum hydroxidehydrogel, whereupon the material is dried and calcined. The metals areincorporated into the calcined material by impregnating the latter withan aqueous solution containing a nickel and a tungsten compound.

The sulphidation, i.e., sulphiding, of the catalysts may be carried outby any method known in the art. Such catalysts have been found to bevery suitable, inter alia, for the preparation of high viscosity indexlubricating oils by hydrocracking a mixture of heavy hydrocarbons andfor application in other processes in which hydrocarbons are convertedat elevated temperature and pressure and in the presence of hydrogen. Aprocess has now been found for the preparation of such a catalyst, inwhich a catalyst can be prepared which is substantially more active thanthat prepared by the known method. According to said process a catalystis prepared by starting from a solution which contains a tungstencompound and an aluminum compound from which a tungsten- andaluminum-containing compound is formed.

SUMMARY OF THE INVENTION

The invention therefore relates to a process for the preparation of asulphided, fluorine-containing nickel-tungsten catalyst, which processcomprises evaporating a solution containing a tungsten compound and analuminum compound to dryness, calcining the resultant product at atemperature from about 500° to about 700° C, then impregnating thecalcined product with a nickel compound, then sulphiding andfluorinating the impregnated product. The invention also relates to aprocess for the conversion of hydrocarbons.

DESCRIPTION OF PREFERRED EMBODIMENTS

The calcination temperature is preferably between 500° and 700° C.Calcination at temperatures lower than 500° C. gives analuminum-tungsten catalyst having a large surface but a structure whichcollapses during sulphidation under usual conditions, which results in acatalyst having a small surface and low viscosity.

Although calcination at temperatures above 700° C. results in stablecatalysts, they have too small a surface.

The atomic Al/W ratio of the aluminum and tungsten compound-containingsolution preferably lies between 0.30 and 1. If a ratio outside thisrange is chosen, then aluminum tungsten compounds are obtained whichexhibit insufficient catalytic activity.

Tungsten compounds which are used are ortho-tungstic acid, meta-tungsticacid, ammonium meta-tungstate.

Ammonium meta-tungstate is preferably used, since the unsuitableammonium is separated from the catalyst material as NH₃ during thecalcination treatment. Aluminum compounds which can be used are aluminumnitrate, aluminum-alpha-ethyl-acetoacetate, aluminum propoxide, aluminumisopropoxide, aluminum lactate.

Most preference is given to aluminum nitrate, since the unsuitablenitrate is separated from the catalyst material as nitrous vapors duringthe calcination treatment.

For the process according to the invention use is made of an aqueoussolution or, if desired, a solution of a polar organic solvent.

Examples of suitable polar organic solvents are: methanol, ethanol,acetone, acetonitrile and diethyl ether.

It is also possible to prepare excellent catalysts by adding aheat-resistant carrier material to the tungsten and aluminumcompound-containing solution. The carrier material is then impregnatedwith said solution.

For this purpose an alumina- and/or silica-containing carrier materialis preferably used, since said material is inert and stable and alsoreadily available. It is also possible to use other carrier materialswith corresponding properties.

Sulphiding of the catalysts may be carried out by any known method. Forexample by contacting the catalysts with sulphur-containing gas such asa mixture of hydrogen and hydrogen sulphide. Another method iscontacting the catalyst with a sulphur-containing hydrocarbon oil suchas a sulphur-containing gas oil.

The fluorination of the catalyst can be carried out by any known methodand for example in situ according to the process described in theNetherlands patent application 7514824 in the name of the Applicant.

This in-situ fluorination of a catalyst is carried out by adding, beforeor during the initial phase of the process in which the catalyst isused, a suitable fluorine compound to the gas and/or liquid stream whichis passed over the catalyst.

As fluorination agent use is preferably made of an organic fluorinecompound.

Examples of suitable organic fluorine compounds for said purposes areortho-fluorotoluene and difluoroethane.

Like the catalysts prepared by known methods, the catalysts according tothe present invention have been found to be particularly suitable foruse in processes for the conversion of hydrocarbons at elevatedtemperature and pressure and in the presence of hydrogen. The inventiontherefore also relates to a process for the conversion of hydrocarbons.

Examples of such processes in which use is made of the catalystsaccording to the invention are the following:

1. the hydrocracking of heavy hydrocarbon oils such as flasheddistillates for the preparation of light hydrocarbon distillates such asgasolines and kerosines.

2. the hydrogenation of aromatics present in light hydrocarbon oildistillates such as kerosines.

3. the hydro-isomerization or hydrocracking of straight-chain paraffinspresent in light hydrocarbon oil distillates in order to raise theoctane number of said distillates.

4. the preparation of high viscosity index lubricating oils by acatalytic hydrogen treatment of heavy hydrocarbon oils such asdeasphalted oils and oil-containing paraffin mixtures.

Especially for the latter process the catalyst according to theinvention has been found to be particularly suitable.

In the latter case the process conditions are as follows:

    ______________________________________                                        pressure       10-200 bar                                                     temperature    300-450° C.                                             space velocity 0.5-10 kg feed/l of cat./h                                     H.sub.2 /oil ratio                                                                           100-5000 Nl hydrogen/kg of feed                                ______________________________________                                    

The invention will be further illustrated with reference to thefollowing examples.

EXAMPLE 1

An aqueous solution of 100 g of ammonium meta-tungstate and 100 g ofaluminum nitrate in 750 ml of water was evaporated to dryness. Theresidue was subsequently calcined at 600° C. for 24 hours.

The resultant Al₂ (WO₄)₃, the yield of which was 106 g, was impregnatedwith 22 g of an aqueous solution of nickel nitrate, dried at 120° C. andsulphided at 450° C. and 10 bar by means of 10% of hydrogen sulphide inhydrogen in order to obtain a catalyst material still to be fluorinated.

The fluorination was carried out in situ by passing a heavy gas oil towhich ortho-fluorotoluene had been added, at a temperature of 450° C.and a pressure of 48 bar and in the presence of hydrogen, over thecatalyst material which was present as a fixed bed in a cylindricalreactor.

EXAMPLE 2

Two catalysts were prepared, in one case Al₂ (WO₄)₃ being deposited onsilicon oxide and in the other on alumina as carrier.

To prepare these catalysts 100 g of carrier was first of all impregnatedwith an aqueous solution of 322 g of ammonium meta-tungstate and 319 gof aluminum nitrate in a quantity of water corresponding to the porevolume of the carrier.

The product was subsequently evaporated to dryness at 120° C. andsubjected to a calcination treatment at 600° C. for 24 hours. Theproduct was then impregnated with an aqueous solution containing 70 g ofnickel nitrate, and sulphided.

To test the activity of these catalysts benzene was subjected to ahydrogenation treatment at a pressure of 48 bar, an H₂ /C₆ H₆ molarratio of 35 and an H₂ /H₂ S molar ratio of 99. The fluorination wascarried out in situ by adding 0.1% by weight of ortho-fluorotoluene tothe benzene feed.

The hydrogenation activity of the catalysts is expressed by the reactionrate constant k of the hydrogenation reaction.

In view of the results stated in the Table it is clear that thehydrogenation activity of the catalysts according to the invention (a, band c) is substantially improved in respect to the activities of thecontrol catalysts d and e stated in the Table. These (commerciallyavailable) catalysts are prepared by impregnating an alumina carrierwith a solution of a nickel salt and a tungstate.

                  TABLE                                                           ______________________________________                                        Activities of some Al.sub.2 (WO.sub.4).sub.3 --containing catalysts with      and                                                                           without a carrier, expressed as the reaction rate constant k of the           hydrogenation reaction of benzene compared with those of some                 Al.sub.2 O.sub.3 --containing catalysts                                       T = 400° C., P = 48 bar, H.sub.2 /C.sub.6 H.sub.6 molar ratio =        35,                                                                           H.sub.2 /H.sub.2 S molar ratio = 99.                                          Cat.  Composition             ml.g.sup.-1.spsp.k h.sup.-1                     ______________________________________                                        a     Ni/Al.sub.2 (WO.sub.4).sub.3                                                    Ni/W = 6/100 w/w      3.5                                             b     Ni/Al.sub.2 (WO.sub.4).sub.3 /SiO.sub.2.sup.α                                                   4.5                                                   14 Ni/23.4 Al/234 W/100 pbw SiO.sub.2                                   c     Ni/Al.sub.2 (WO.sub.4).sub.3 γ Al.sub.2 O.sub.3.sup.β              9 Ni/15.6 Al/156W/100 pbw Al.sub.2 O.sub.3                                                            3.5                                             d     In comparison                                                                 100 Al.sub.2 O.sub.3 /15Ni/39W pbw                                                                    2.7                                             e     100 Al.sub.2 O.sub.3 /9Ni/41W pbw                                                                     1.8                                             ______________________________________                                         .sup.α surface SiO.sub.2 = 330 m.sup.2 /g                               .sup.β surface Al.sub. 2 O.sub.3 = 205 m.sup.2 /g                   

What is claimed is:
 1. A process for the hydroconversion of hydrocarbonoil which comprises contacting said oil in a reaction zone at elevatedtemperature and pressure and in the presence of hydrogen with asulphided fluorine-containing nickel-tungsten catalyst prepared byevaporating to dryness a solution containing a tungsten compound and analuminum compound having an atomic ratio Al/w in the range of 0.3-1,calcining the resultant product at a temperature from about 500° C. to700° C., impregnating the calcined product with a nickel compound, thensulphiding and fluorinating the impregnated product, and passinghydroconverted product from said reaction zone.